Figure 12.28Health consequences of a loss of control The “executive” rat at the left can switch off the tail shock by turning the wheel. Because it has control over the shock, it is no more likely to develop ulcers than is the unshocked control rat on the right. The “subordinate” rat in the center receives the same shocks as the executive rat, but with no control over the shocks. It is, therefore, more likely to develop ulcers. (Adapted from Weiss, 1977.)